Citrus rootstock named &#39;UFR-1&#39;

ABSTRACT

‘UFR-1’ is a new and distinct allotetraploid citrus rootstock for tree size control and improved disease resistance. ‘UFR-1’ has shown a positive reaction to the Huanglongbing disease (HLB, or citrus greening disease) in multiple experimental field trials. Scion trees grafted on this rootstock show a reduced frequency of infection and reduced disease symptoms once infected as compared to commercial diploid rootstocks.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/942,571, filed Feb. 20, 2014, herein incorporated by reference in itsentirety.

BACKGROUND OF THE INVENTION

Latin name of the genus and species of the plant claimed: Citrusreticulata/Citrus paradisi+Citrus grandis×Citrus reticulata+Poncirustrifoliata

Variety denomination: ‘UFR-1’

The present invention relates to a new and distinct variety of citrusrootstock named ‘UFR-1’. The Plant Improvement Team in Lake Alfred, Fla.has pioneered the development and testing of allotetraploid citrusrootstocks. ‘UFR-1’ (identified as Orange #3 in field trials) is anallotetraploid zygotic hybrid derived from a conventional cross of twosomatic hybrids previously produced by protoplast fusion. The somatichybrid seed parent is ‘Nova’ mandarin hybrid+Hirado Buntan pummelo(zygotic seedling), and the somatic hybrid pollen parent is Cleopatramandarin+Argentine trifoliate orange.

BRIEF SUMMARY OF THE INVENTION

‘UFR-1’ was selected as a potential citrus rootstock on the basis of itspositive reaction to Huanglongbing disease (HLB, or citrus greeningdisease) in multiple experimental field trials. Scion trees grafted onto‘UFR-1’ showed a reduced frequency of infection and reduced diseasesymptoms once infected when compared to other commercial diploidrootstocks. Although scion trees grafted onto ‘UFR-1’ grow off quickly,the trees remain small in size, making ‘UFR-1’ suitable for use inAdvanced Citrus Production Systems that feature high density plantings.‘UFR-1’ produces adequate nuclear seed, making it amenable to standardnursery propagation practices for uniform liner production. ‘UFR-1’exhibited salinity tolerance in a greenhouse study (Grosser et al.,2012), and tolerance of the Diaprepes/Phytophthora complex in a separategreenhouse study (Grosser et al., 2003). Long-term performance of treeson this rootstock selection is unknown. Yield and fruit quality data islimited, but 3 years of data from young trees (the St. Helena project,see Table 1) indicates good productivity and fruit quality. Tolerance tocitrus blight is also unknown, but under investigation. True-to-typenessthrough asexual reproduction was demonstrated by topworking UFR-1 onto aCarrizo citrange rootstock in Lake Alfred, Fla. Seed from this topworkedtree and from the original tree are predominantly of nucellar origin,producing true-to-type seedlings.

TABLE 1 Rootstock Data from 5-year old trees in the St. Helenatrial-Dundee, FL. Lbs Yield Boxes/Tree Cumulative Solids/Box 2011 20122013 Yield Scion Type Rootstock 2012 2013 (35 mo.) (47 mo.) (59 mo.)(Boxes) VALQUARIUS Som. Hyb. ‘UFR-6’ 5.64 5.43 0.5 0.78 1.94 3.22 VERNIASom. Hyb. ‘UFR-6’ 5.67 6.01 0.4 0.63 1.41 2.44 VALQUARIUS Tetrazyg‘UFR-1’ 5.5 4.87 NS 0.72 2.23 2.95 VERNIA Tetrazyg ‘UFR-1’ 5.61 6.280.31 0.67 1.33 2.31 VERNIA Tetrazyg ‘UFR-2’ 5.47 5.93 0.35 0.25 1.381.98 VALQUARIUS Tetrazyg ‘UFR-2’ 4.57 5.37 NS 0.75 1.73 2.48 VALQUARIUSTetrazyg ‘UFR-3’ 4.84 5.05 NS 0.81 1.97 2.78 VERNIA Tetrazyg ‘UFR-3’5.46 5.82 0.37 0.38 1.82 2.57 VERNIA Tetrazyg ‘UFR-4’ 5.79 6.07 0.540.71 1.73 2.98 VALQUARIUS Tetrazyg ‘UFR-4’ 4.65 5.07 NS 0.65 1.59 2.64VALQUARIUS Tetrazyg ‘UFR-5’ 5.76 5.72 0.33 0.56 1.80 2.69 VERNIATetrazyg ‘UFR-5’ 5.89 5.34 0.42 0.25 1.93 2.60 VALQUARIUS Diploid FG1731 5.83 6.81 NS 0.68 2.20 2.88 VALQUARIUS Diploid FG 1733 5.12 5.63 NS0.67 2.77 3.44 VERNIA Diploid SWINGLE* 5.11 5.79 0.33 0.85 1.08 2.26VALQUARIUS Diploid SWINGLE* NS 5.61 NS NS 1.50 1.50 VERNIA Diploid CLEO*4.79 5.51 NS 0.50 0.83 1.33 VALQUARIUS Diploid CLEO* NS 5.21 NS NS 1.71.7 VERNIA Diploid R. LEMON* 3.67 na NS 0.78 na 0.78 VALQUARIUS DiploidVOLK* NS 4.12 NS NS 2.58 2.58 VERNIA Diploid VOLK* 3.6 4.73 0.4 1.130.83 2.36 VALQUARIUS Diploid KUHARSKE NS 5.75 NS NS 2.2 2.2 VERNIADiploid KUHARSKE 4.34 5.83 0.15 0.75 1.08 1.98 NS—not significant fruit;na—data not available; *—control commercial rootstock One box containsapproximately 90 lbs. fruit.

BRIEF DESCRIPTION OF THE DRAWINGS

‘UFR-1’ is illustrated by the accompanying photographs, which show thetree's form, foliage, and fruit. The colors shown are as true as can bereasonably obtained by conventional photographic procedures. Thephotographs are of a tree approximately 10 years old. All figures weretaken in the fall of 2013.

FIG. 1.—Shows a close-up of the nearly mature fruits with the rind andcross-sectional view of the fruit when cut in the center.

FIG. 2.—Shows the overall mature plant growth habit.

FIG. 3.—Shows a close-up of the mature growth habit.

FIG. 4.—Shows a close-up of leaves and nearly mature fruits.

FIG. 5.—Shows a close-up of nearly mature fruits.

FIG. 6.—Shows a close-up of seeds from nearly mature fruit.

DETAILED BOTANICAL DESCRIPTION

The following detailed description sets forth the distinctivecharacteristics of ‘UFR-1’. The colors (except those in common terms)are described from the R.H.S.

Colour Chart published by The Royal Horticultural Society in London(second edition), in association with the Flower Council of Holland.

-   Phenotypic description of Citrus reticulata/Citrus paradisi+Citrus    grandis×Citrus reticulata+Poncirus trifoliata ‘UFR-71’:-   Classification:    -   -   Botanical.—[Citrus reticulata hybrid (Clementine            mandarin×Orlando tangelo) Citrus reticulata×Citrus            paradisi)+Citrus grandis]×[Citrus reticulata+Poncirus            trifoliata (trifoliate orange)].        -   Common name.—Complex allotetraploid ‘tetrazyg’ rootstock            hybrid.-   Parentage:    -   -   Female parent.—‘Nova’ mandarin+Hirado Buntan pummelo            (zygotic seedling) somatic hybrid (unpatented).        -   Male parent.—Cleopatra mandarin+Argentine trifoliate orange;            somatic hybrid (unpatented).-   Tree:    -   -   Ploidy.—Tetraploid.        -   Size.—Medium-large.        -   Height.—3.65 meters.        -   Tree spread.—4.2 to 4.3 meters.        -   Vigor.—Moderately vigorous.        -   Density.—Canopies are moderately dense.        -   Form.—The tree is obloid-shaped with lateral and upright            branches growing toward low to medium angles. Branches with            fruit exhibit drooping.        -   Growth habit.—Both upright and lateral growth with a low to            medium angle.-   Trunk:    -   -   Trunk diameter.—19.5 cm in diameter at 30 cm above the            ground on a 10-year-old tree.        -   Trunk texture.—Smooth.        -   Trunk bark color.—RHS 197A (greyed-green); irregularly            striated with RHS N189A (green).-   Branches:    -   -   Crotch angle.—First crotch forms 30- to 35-degree angle,            middle crotch forms a 45-degree angle.        -   Branch length.—Branch reaches 2.7 meters from the first            crotch to the tip of the branch.        -   Branch texture.—Relatively rough with small thorns or            spines.        -   Branch color (shoots from previous flush, hardened and 4 to            5 mm in diameter).—RHS N137A (green).-   Leaves:    -   -   Size (lamina average).—Length: 93.2 mm Width: 51 mm L/W            ratio: 1.8.        -   Thickness.—Thicker than average diploid citrus rootstock            hybrids.        -   Type.—Mostly simple leaf types, occasionally with bifoliate            and trifoliate types of leaves appearing within the same            tree.        -   Shape.—Elliptical.        -   Apex.—Retuse.        -   Base.—Acute to sub-obtuse.        -   Margin.—Entire and slightly undulate.        -   Surface.—Upper surface: Glabrous Lower surface: Medium veins            that are pinnately netted.        -   Color.—Upper surface (adaxial): RHS N137A (green) Lower            surface (abaxial): RHS N137D (green).        -   Petiole.—Shape: Brevipetiolate (shorter than leaf lamina);            junction between petiole and lamina is articulate Width            (petiole wing): Narrow Shape (petiole wing): Obovate Length:            14.4 to 18 mm Width: 4.5 to 4.7 mm Color: RHS N137A (green).-   Flowers and flower buds:    -   -   Type.—Hermaphrodite.        -   Bearing.—Flowers grow from leaf axillaries and leaf            terminals singly and in small clusters; most single flowers            grow from leaf axillaries.        -   Flower bud size.—Shape: Initial visible flower bud has a            round ball shape; mature flower bud has an elongated olive            shape.        -   Flower petals.—Shape: Flat, spatula-shaped Apex shape:            Smooth, acute-shaped Base shape: Even obtuse Margin: Smooth.        -   Flower sepal.—Shape: Delta-shaped with an acute angle at the            apex Apex shape: Triangle-shaped Margin: Smooth.        -   Fragrance.—Fragrant/Moderately fragrant.        -   Reproductive organs.—Fertility: Appears self-fertile Pollen            amount: Abundant/Moderate amount Pollen color (general):            Bright-yellow Ovary shape: Oval-shaped.-   Fruit:    -   -   Size.—Uniform.        -   Height.—50 to 55.8 mm on average.        -   Width.—66 to 75 mm on average.        -   Average weight (per individual fruit).—138 grams.        -   Shape.—Round.        -   Shape (cross-section).—Round.        -   Apex.—Truncated with slight dent.        -   Apex cavity diameter.—5.2 mm.        -   Base cavity diameter.—5.8 to 7.5 mm.        -   Base.—No neck.        -   Harvesting.—Fruit can be harvested from October through            December in Florida.        -   Fruit stem (short stem connecting the fruit).—Length: 8.1 mm            Diameter: 4.9 mm Color: RHS 143B (green) with RHS 195B            (grey-green) strip.-   Rind:    -   -   Adherence.—Adherence between albedo (mesocarp) and flesh            (endocarp) is medium. The adherence is evenly distributed            from base to apex.        -   Thickness.—3.4 to 4.8 mm on average.        -   Texture.—Smooth.        -   Color.—Flavedo (epicarp): Ranges between RHS 151B            (yellow-green) to RHS 151 A (yellow-green) Albedo            (mesocarp): RHS 157D (green-white).        -   Stylar end.—Closed.        -   Rind oil cell density.—62 oil cells/square cm.-   Flesh:    -   -   Number of segments.—Between 7 and 8 segments per fruit on            average.        -   Segment walls.—Firm with sufficient strength to maintain            integrity as separated.        -   Juice.—Abundant.        -   Color.—Uniformly RHS 11 C (yellow).        -   Texture.—Soft.        -   Vesicles.—Length: Arranged from 13 to 15.6 mm on average            Diameter (thickness): 2.3 to 3.3 mm on average.        -   Eating quality.—N/A.        -   Juice index.—Soluble solids (average): 9 Brix.-   Seeds:    -   -   Type.—Polyembryonic.        -   Number.—Ranges from 4 to 16. Most fruit contains less than            10 seeds.        -   Shape.—Seed shapes are not uniform. Normal seeds are mostly            ventricose/swollen-shaped and clavate club shaped.        -   Size.—Length: 14.5 to 16.4 mm Width: 5.9 to 6.9 mm.        -   Seed coat color.—Outer Surface: RHS 155A (white) and            wrinkled Inner surface:. RHS 164C (greyed-orange) Cotyledon            color: RHS 145D (yellow-green).-   Resistance to disease: ‘UFR-1’ rootstock was selected on the basis    of its positive reaction to HLB disease (huanglongbing or citrus    greening disease) in multiple field trials. Trees on this rootstock    show a reduced frequency of infection and reduced disease symptoms    once infected, as compared to commercial diploid rootstocks.

What is claimed is:
 1. A new and distinct citrus rootstock cultivar asillustrated and described herein.